Petroleum Refining and Examining Petroleum

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Petroleum Refining and Examining Petroleums
Molecules
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Separating crude

• Crude oil is a complex mixture of many compounds
• Distillation is used to separate these compounds
  into distinctive mixtures (fractions)
• Process is called fractional distillation (or
  fractionation)

Crude distillation unit, Petroleum Institute
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Fractional distillation

1. Crude oil is heated to about 400C in a furnace
2. Pumped into base of a distilling column
   (fractionating tower), usually more than 30 m
   tall
3. Smaller molecules that vaporize, rise to the top
   where they either condense or stay vapors
4. Large molecules have higher boiling points and
   they condense and sink to the bottom where they
   are eventually vaporized or remain liquid

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Distillation
Institute of Petroleum
ChemCom
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Petroleums molecules

• Small hydrocarbons (those with one to four carbon
  atoms) have low boiling points
• They are only slightly attracted to each other
• Forces of attraction between molecules
  intermolecular forces
• They readily separate from each other and rise
  through distillation column as gases

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• Large hydrocarbons (five to twenty carbon atoms)
  tend to stay as liquid
• Include gasoline, kerosene, and heavier oils
• Those with more carbon atoms are found in the
  greasy fraction, called the bottoms
• They are solid at room temperature and never
  vaporize in column

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Assignment

• Hydrocarbon boiling points
• p. 220 1-6